class/System/System.ComponentModel.Design.Serialization/MemberRelationshipService.cs

   1 //
   2 // System.ComponentModel.Design.Serialization.MemberRelationshipService
   3 //
   4 // Authors:
   5 //        Ivan N. Zlatev (contact@i-nZ.net)
   6 //
   7 // (C) 2007 Ivan N. Zlatev
   8
   9 //
  10 // Permission is hereby granted, free of charge, to any person obtaining
  11 // a copy of this software and associated documentation files (the
  12 // "Software"), to deal in the Software without restriction, including
  13 // without limitation the rights to use, copy, modify, merge, publish,
  14 // distribute, sublicense, and/or sell copies of the Software, and to
  15 // permit persons to whom the Software is furnished to do so, subject to
  16 // the following conditions:
  17 //
  18 // The above copyright notice and this permission notice shall be
  19 // included in all copies or substantial portions of the Software.
  20 //
  21 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  22 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  23 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  24 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  25 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  26 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  27 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  28 //
  29
  30 #if NET_2_0
  31
  32 using System;
  33 using System.CodeDom;
  34 using System.ComponentModel;
  35 using System.Collections;
  36
  37 namespace System.ComponentModel.Design.Serialization
  38 {
  39         public abstract class MemberRelationshipService
  40         {
  41
  42                 // MSDN: The default implementation stores relationships in a dictionary using weak references
  43                 //       so the relationship table does not keep objects alive.
  44                 //
  45                 private class MemberRelationshipWeakEntry
  46                 {
  47
  48                         private WeakReference _ownerWeakRef;
  49                         private MemberDescriptor _member;
  50
  51                         public MemberRelationshipWeakEntry (MemberRelationship relation)
  52                         {
  53                                 _ownerWeakRef = new WeakReference (relation.Owner);
  54                                 _member = relation.Member;
  55                         }
  56
  57                         public object Owner {
  58                                 get {
  59                                         if (_ownerWeakRef.IsAlive)
  60                                                 return _ownerWeakRef.Target;
  61                                         return null;
  62                                 }
  63                         }
  64
  65                         public MemberDescriptor Member {
  66                                 get { return _member; }
  67                         }
  68
  69                         public static bool operator == (MemberRelationshipWeakEntry left, MemberRelationshipWeakEntry right)
  70                         {
  71                                 if (left.Owner == right.Owner && left.Member == right.Member)
  72                                         return true;
  73                                 else
  74                                         return false;
  75                         }
  76
  77                         public static bool operator != (MemberRelationshipWeakEntry left, MemberRelationshipWeakEntry right)
  78                         {
  79                                 return !(left == right);
  80                         }
  81
  82                         public override int GetHashCode ()
  83                         {
  84                                 if (this.Owner != null && _member != null)
  85                                         return _member.GetHashCode () ^ _ownerWeakRef.Target.GetHashCode ();
  86                                 return base.GetHashCode ();
  87                         }
  88
  89                         public override bool Equals (object o)
  90                         {
  91                                 if (o is MemberRelationshipWeakEntry) {
  92                                         return ((MemberRelationshipWeakEntry) o) == this;
  93                                 }
  94                                 return false;
  95                         }
  96                 }
  97
  98                 private Hashtable _relations;
  99
 100                 protected MemberRelationshipService ()
 101                 {
 102                         _relations = new Hashtable ();
 103                 }
 104
 105                 public abstract bool SupportsRelationship (MemberRelationship source, MemberRelationship relationship);
 106
 107                 protected virtual MemberRelationship GetRelationship (MemberRelationship source)
 108                 {
 109                         if (source.IsEmpty)
 110                                 throw new ArgumentNullException ("source");
 111
 112                         MemberRelationshipWeakEntry entry = _relations[new MemberRelationshipWeakEntry (source)] as MemberRelationshipWeakEntry;
 113                         if (entry != null)
 114                                 return new MemberRelationship (entry.Owner, entry.Member);
 115                         return MemberRelationship.Empty;
 116                 }
 117
 118                 protected virtual void SetRelationship (MemberRelationship source, MemberRelationship relationship)
 119                 {
 120                         if (source.IsEmpty)
 121                                 throw new ArgumentNullException ("source");
 122
 123                         if (!relationship.IsEmpty && !this.SupportsRelationship (source, relationship))
 124                                 throw new ArgumentException ("Relationship not supported.");
 125
 126                         _relations[new MemberRelationshipWeakEntry (source)] = new MemberRelationshipWeakEntry (relationship);
 127                 }
 128
 129                 public MemberRelationship this [object owner, MemberDescriptor member] {
 130                         get { return GetRelationship (new MemberRelationship (owner,  member)); }
 131                         set { SetRelationship (new MemberRelationship (owner,  member), value); }
 132                 }
 133
 134                 public MemberRelationship this [MemberRelationship source] {
 135                         get { return GetRelationship (source); }
 136                         set { SetRelationship (source, value); }
 137                 }
 138         }
 139 }
 140 #endif